Pump



varieties of materials as roller elements.

pump to a practical dynamic or United States Patent O 3,316,852 PUMPHarry J. Sarller, Minneapolis, Minn., assignor to Hypro, Inc.,Minneapolis, Minn., a corporation of Ohio Continuation of applicationSer. No. 419,022, Dec. 17, 1964. This application Sept. 22, 1966, Ser.No. 584,628 14 Claims. (Cl. 103-136) The present invention relates torotary pumps and more particularly to rotary pumps of the type whichemploy free floating roller elements, and is a continuation of myco-pending application Ser. No. 419,022, filed Dec. 17, 1964, andentitled, Pump.

In the normal performance of pumps, it is generally desirable to providea pump unit which has high capacity for its size and which is economicalto produce in a manufacturing operation. As a class, roller pumpsgenerally meet these desirous performance characteristics, and havecertain performance parameters which adapt them to use in a wide varietyof applications. Roller pumps are defined generally in United StatesPatents 2,765,745 and 3,119,345, the former patent defining aside-ported unit, the latter patent defining an end-ported unit. Each ofthese patents is assigned to the assignee of the present invention.

Since the output of a roller pump is a result of work performed by theindividual roller elements, any manner of eliminating or reducing rollerwear will enhance the overall operation of the pump. The improved rotordesign of i the present invention is one which substantially reducesroller wear, and thus increases the life of the roller for a givenapplication, and also permits the use of new The adaptability of rollerpumps to a wider variety of applications generally is thereforeaccomplished.

In accordance with the present invention, a roller pump is providedhaving a cylindrical pumping chamber with an improved rotor journaledfor rotation therewithin. The rotor has a modified slot or rollerreceiving design for enhancing the over-all operation of the pump. Theimproved rotor has arcuately spaced roller receiving slots, each slotbeing defined by angularly disposed leading and trailing faces, thetrailing face being located substantially along a radius line throughthe central axis of the rotor. This design permits a more extended orextensive trailing edge to be employed, thus increasing the capacity ofthe maximum for the housing size employed, increasing the pressurecapability by improving the running seal, and also limiting orpractically eliminating any possibility of scuffing action between thesurfaces of the roller receiving slot of the rotor and the body of theroller per se. Furthermore, the need for a scoop to be formed in therotor adjacent to the roller receiving slots is eliminated by the designof the present invention, thereby increasing the area of restrictiondefined between the rotor surface and the housing surface. This increasein area eflfectively enhances the valving action between adjacent slots,increases the area of contact that the roller makes with the rotorsurface, reduces wear on the rollers, and reduces clattering orchattering of the rollers between opposed faces of the roller receivingslots particularly as the rotor, in a dynamic situation, traverses thezone between the suction side and the pressure side of the pump. Therotor design is also adaptable for simple reversal of rotationfo rrunning.

Therefore, it is an object of the present invention to provide animproved rotor design for roller pumps which increases the capacity andpressure capability of the pump to a practical maximum permissible bythe configuration of the pump housing.

It is a further object of the present invention to provide an improveddesign for a rotor for roller pumps which will 3,316,852 Patented May 2,1967 permit the leading and trailing surfaces of each roller receivingslot to act as an efiicient low friction dynamic or running seal in thesector between the angularly spaced inlet and outlet ports of the pumpchamber.

It is yet a further object of the present invention to provide animproved rotor design having rotor receiving slots arranged in angularlyspaced disposition therearound, each slot having a bottom surface and apair of angularly disposed leading and trailing faces arranged inradially outwardly diverging relationship, the slot design providingimproved pumping action manifested by increased efficiency and reductionof noise and wear in the various pump components.

It is still a further object of the present invention to provide a pumpdesign which will accommodate either end-porting or side-portingarrangements such that fluid flow may be established through the pumpwith either circumferential or cir-cumferential-transverse displacement.

Other and further objects of the present invention will become apparentto those skilled in the art upon a study of the following specification,appended claims, and accompanying drawings, wherein:

FIGURE 1 is an end elevational view of a pump construction exemplifyingthe invention, and being particularly adapted to utilize the improvedrotor of the present invention, the side inlet being shown in a blockedor plugged condition, and the end outlet being similarly plugged orblocked;

FIGURE 2 is a vertical sectional view taken along the line and in thedirection of the arrows 2-2J of FIGURE 1;

FIGURE 3 is a view corresponding to FIGURE 1 but with the detachable endwall or face plate of the pump being removed, the view showing theconfiguration of the improved rotor structure, and being taken along theline and in the direction of arrows 3-3 of FIGURE 2;

FIGURE 4 is a view of the inside face of the detachable end wall or faceplate, the view being taken along the line and in the direction ofarrows 4-4 of FIGURE 2;

FIGURE 5 is a horizontal sectional view taken along the line and in thedirection of the arrows 5-5 of FIG- URE 1;

FIGURES 6 is a perspective view of a rotor together with itsaccompanying shaft, the view illustrating the specific design of theroller receiving slots which are formed in the rotor; and

FIGURE 7 is a view similar to FIGURE 3 showing a rotor with a somewhatmodified configuration.

Referring now in detail to the drawing which illustrates the preferredembodiment of the present invention, the rotary pump selected toillustrate the invention together with its environment and use comprisesa housing generally designated 10 and a rotor assemblage generallydesignated 12 which is journaled therein. The housing 10 includes acup-shaped body 14 having an integral plate or end wall 16 and anintermediate circumferential wall 18. Additionally, the housing 10includes a removable or detachable face plate or end wall 20. The endwall 20 is provided with quadrantly spaced holes 21 (FIG- URE 4). Theupper two holes accommodate a pair of tap screws 22 that extend into twotapped upper holes 24 (FIGURE 3) located in the cup-shaped body 14. In asomewhat similar fashion, a pair of threaded studs 26 are anchored in apair of tapped lower holes 28 in the cup- More specifically,

a pair of retaining cuts 32 being provided to act in this capacity.

The integral end wall 16 and the intermediate circumferential wall 18 ofthe cup-shaped body 14 in combination with the removable end wall 20forms a cylindrical pumping chamber 34. Leading into the pumping chamber32 from one side is an inlet port 36a, as best shown in FIGURE 5, thisport being located in the wall 18. End inlet port 36b, as shown inFIGURES 4 and 5, leads into the pumping chamber 34 through the wall 20.As best viewed in FIGURES 4 and 5, the end inlet port is divided bymeans of an arcuate rib 38. The side inlet port 3611 has directcommunication with an inlet 40a, Whereas the end inlet port 36b hasdirect communication with an inlet 40b. The inlet 40a is formed byreason of an internally threaded boss 42a and the inlet 40b is similarlyformed by an internally threaded boss 42b. A side outlet port 44a, asshown in FIGURE 5, is formed in the wall 18 and an end outlet port 44bas illustrated in FIGURES 4 and is provided in the wall 20. As with theend inlet port 361;, the end outlet port 44b is divided by an arcuaterib, the rib bearing the reference numeral 45. Directly communicatignwith the outlet numeral 45. Directly communicating with the outlet ports44a and 44b are outlets 48a and 48!) respectively, which are formed byreason of internally threaded bosses 50a and 501).

As illustrated in FIGURE 2, the end walls 16 and 20 are provided withoppositely directed bosses 52, each of which contains a bearing 54 and ashaft seal 46. These walls 16 and 20 additionally include aligned shaftopenings 58. The end wall 16 is formed with a shallow cavity 60, asshown in FIGURE 3, which communicates with a small passageway 62 leadingfrom a space or void 64 between the end wall 16 and the shaft seal 56nearest thereto, the passageway extending to a point of reduced pressurewithin the pumping chamber 34. In a similar fashion, a passageway 66 inthe wall 20 extends from a space or void 63 between the wall 20 and theseal 56 adjacent thereto to the inlet port 30b which is, of course, at apoint of'reduced pressure.

Describing now the rotor assemblage 12, with particular attention beingdirected to FIGURES 3 and 6 of the drawings, it will be observed thatthis assemblage includes a rotor body 70 appropriately secured, as byset screw 75 or alternatively by key means (not shown) to a shaft 72passing through the previously mentioned shaft openings 58 and beingjournaled in the bearings 54. The shaft is driven by a source ofrotative power (not shown) in the direction indicated by arrow 74. Inother words, the shaft 72 and the rotor body 70 mounted thereon arerotated in a clockwise direction as viewed in FIGURE 3. As is customaryin pumps of this type, the axis of rotation of the rotor body 70 isoffset from the central axis of the cylindrical pumping chamber 34.

From FIGURES 3 and 6, it can be seen that the rotor body 70 is formedwith a plurality of roller receiving slots 76 that extend radiallyinwardly from the periphery of the rotor and also extend across theentire width thereof. In other words, the slots 76 are substantiallycoextensive in length with the axial length of cylindrical pumpingchamber 34. The slots 76, therefore, each have a bottom surface 78together with a leading face 80 and a trailing face 82, the leading andtrailing faces 80 and 82 being generally angularly oriented, one toanother, in radially outwardly diverging relationship. The leading andtrailing faces 80 and 82 are preferably disposed at an acute angle ofbetween 30 and 50, one to another. this angle is between about 35 and45, and preferably about 45. In operation, the trailing face 82 providesa driving face for the roller which is retained within the slot, and itwill be observed that this trailing face 82 is disposed along a radiusline or along a plane passing through the center of the rotor body 70.Thus, the trailing face 82 extends along substantially a full dimensionor full radius of the pumping chamber thus utilizing the maximumavailable capacity of the pumping chamber for controlling the rollerdisposition during the pumping action. For reasons to be given below,scufiing action on the surface of the roller is substantially eliminatedby this design.

Disposed in each of the individual slots 76 and coextensive with thelength thereof is a cylindrical roller element 86 that is movableinwardly and outwardly within its particular slot. The roller elements86 sequentially produce the requisite pumping action as they moveradially inwardly and outwardly with rotation of the rotor body 70.

The clearance available between each roller member 86 and each leadingedge of the slot permits free flow of fluid within the individual slots76, and also renders the pump capable of being ported universally, thatis, either side ported or end ported as shown in the drawings. Inaddition, the slot design prevents vibration of the pump duringoperation because of the improved valving between adjacent slots asprovided by the uniformly formed solid webs defined by adjacent leadingand trailing faces.

Because of the positioning of the trailing face, that is, along theradius line of the rotor, it is possible to extend this face to a pointwhich is below the center line or center axis of the roller while stillmaintaining a proper circumferential clearance between the rotor and thehousing surface. For a roller having a diameter of 0.675 inch,

an extension of the trailing face of about 0.045 inch below the centerline of the roller when the roller is in fully extended position hasbeen found to be useful. Other rotor sizes may be similarlyproportioned. The roller materials may be nylon, hard rubber or thelike, the improved rotor design making it possible to employ rollermaterials which previously have been found unsuitable for this type ofpumping operation. Because of the narrow clearance which exists at theupper end of the pumping chamber, this is being made possible bylocating the trailing face 82 along a radius line of a rotor, andbecause of the design of the roller receiving slot, there is lesstendency during operation for the individual roller to be sharply drivenor drawn across the slot by the pressure gradient which exists in theseal area or sector and vacuum sides of a pumping chamber, thuseliminating clatter and its accompanying roller scuffing. This featureis equally true when the individual rollers are at the fully extendeddisposition at the 6 oclock position in the pumping chamber asillustrated in FIGURE 3.

Each roller receiving slot is designed and dimensioned to receive itsroller in a particular manner. The roller is never confined tightlybetween the leading face 80 and the trailing face 82, but when fullyretracted within the slot 76, may rest against the substantially planarbottom surface 78 without contacting either leading face 80 or trailingface 82. In a running condition, when the rotor is in the center of theseal area or sector, such as in a 12 oclock position in FIGURE 3, theroller extends substantially between the inner surface of the housingchamber and the bottom surface 78 of the roller receiving slot.

While approaching this 12 oclock position, the roller contacts the innersurface of the pumping chamber and the trailing edge 82 of the slot 76.Upon reaching the top or 12 oclock position, the roller will be insubstantially mutual contact with the surface of the pumping chamber andthe bottom of the slot 76 while transversing the path from the trailingface to the leading face. Upon leaving the center of the seal area, the12 oclock position, the pressure diiferential in the areas of thechamber between the pressure side and the vacuum side will drive theroller from the trailing face 82 toward the leading face 80. Since theslots 76 are sufficiently wide, the rollers are free to so move andfluid is also free to move into and out of the confines of the slot.This arcuate movement of the rollers is smooth and no scoop or rotorbottom surface,

porting arrangement is necessary. The leading face 80 is thereforeplanar and offers a broad contacting surface area for the rollers,thereby reducing roller wear when contact is made between the rollersurface and this leading face. Therefore, the depth of the rollerreceiving slots 76 is substantially equal to the diameter of the rollerretained therein, and the allowances being made for running tolerances,width dimension of these outwardly diverging slots at the bottom ornarrowest point exceeds the radius of the roller. Additionally, thewidth dimension of these slots 76 measured or taken along a plane whichpasses through the central axis of a roller and intersecting both theleading face and trailing face thereof is always greater than thediameter of the individual 1 rollers. For a 31.85 inch diameter rotorhaving 8 slots,

and using 0.675 inch diameter rollers, a bottom width of 0.5 inch with a45 divergence angle has been found satisfactory.

It is a feature of this arrangement that roller wear is reduced andtherefore a wider range of roller materials may be used. It is a furtherand significant feature of this arrangement that the output curve isflattened, that is, the output does not drop rapidly with an increase inpressure. The slot width and configuration provides for exceptionallysmooth running of the pump. Thus, as the roller is moving between, forexample, the pressure sector and the suction sector, there will be atendency to transfer the roller from a disposition adjacent the trailingsurface to a disposition adjacent the forward surface. In the structureas provided herein, this transfer is smooth,

- gentle, and is accomplished without any unusual roller wear beingexperienced. As previously indicated, the walls of the rotor slots areplanar, and there is no unusual occurrence of discontinuities which willtend to render the surface forces concentrated so as to increase therate of roller wear. When seated in the roller slot, contact isavailable between the roller and the slot walls against the and one orthe other of the leading or trailing surfaces. The Width is wide enoughat this point to accommodate the roller in either disposition.

By a similar fashion, as the individual rollers traverse the areabetween the suction side and the pressure side, they are free to moveagainst the surfaces of the slots in such a fashion that chattering isgenerally avoided, and since the surfaces of the slots are planar,concentrations of contact area are avoided and the pressure contact isavailable across the entire surface of the slot faces. In this fashion,enhanced valving action is available to permit fluid to freely flow onall sides of the rollers as they move radially within the confines ofthe individual slots.

In the general operation of the pump, the shaft 72 together with rotorbody 70 rotates in the direction of the arrow 74, this being in aclockwise direction, as viewed in FIGURES 1, 3 and 6. The various rollerelements 86 are forced outwardly by the centrifugal force present in thedynamically moving system so as to ride against the inner surface of thecircumferential wall 18.. In this regard, it will be remembered that theroller elements are free to move within the slots 76, the rollerelements being carried along with the rotor by'reason of the engagementof the roller elements with the respective trailing face 82 of theindividual slot 76 within which the roller is positioned. The rotor body70 has its ends residing in a. proximal relationship with the end walls16 and 18, with normal running clearances or tolerances being utilized.Hence, the roller elements 86 are prevented from shifting or movingaxially within the individual slots 76.

As best seen in FIGURE 3, as the roller elements 86 move intojuxtaposition with the inlet ports 36a and 36b, fluid will be drawn orsucked through the particular inlet ports 36a and 36b (or both)depending upon which are operative, being unblocked orunplugged andaccordingly coupled to a suitable source of fluid. When the side inletport 36a is plugged as indicated at 88, under these cir- 6 cumstances,the fluid will be drawn in by way of the inlet port 3612. While underthese assumed conditions, the fluid originally enters between the bottom78 of the particular slots 76 which pass the inlet port 36b. The fluidis further caused to be drawn into the space between the intermediatecircumferential wall 18 and the periphery of the rotor body 70 due tothe action derived from the preceding roller 36. In this regard, it.will be recalled that the leading face 82 of each slot 76 is generallyangularly oriented with regard to the trailing face so that thisspecific type of pumping action is believed to be occurring.

As the roller elements 86 are progressively moved from a horizontal or 3oclock position to a bottom or 6 oclock position, more and more fluid isdrawn into the regions between the cylindrical roller elements 86 andthe bottom 78 of the various individual slots 76. However, as the rollerelements 86 are moved upwardly from their lowermost successive positionstoward a horizontal 9 oclock position, the region or volume intermediatethe circumferential wall 18 and the periphery of the rotor body 70decreases, as is clearly visible in FIGURE 3, and the progressivedecrease causes the entrapped fluid to be forced outwardly through theoutlet port 44a inasmuch as the outlet port 44b is shown blocked by theplug 90. Thus, communication is provided in such a fashion that thefluid will be discharged through the pipe 94.

When the end inlet port 36b is blocked and the side inlet port 36a isopen, the pipe 92a shown in phantom outline is connected to theinternally threaded boss 42a, and the plug 88 is placed in the boss 42b.Similarly, the pipe 94a can be utilized as the outlet conduit, the plug90 then being positioned in the boss 50a.

In the modified situation mentioned above, it is readily apparent thatas the various roller elements 86 pass the inlet port 36a, fluid will bedrawn into the region between the circumferential wall 18 and theperiphery of the rotor body 70. As the rotor carries the roller elementsaround the chamber, the confined fluid will be forced outwardly becauseof the space between the circumferential wall 18 and the periphery ofthe rotor body 70 gradually decreases. Any fluid between thecircumferential wall 18 and the periphery of the rotor bodies 70 will beforced into the roller slots and thence outwardly through the now openoutlet port 4%. It will be remembered that the plug 90 has, for the sakeof discussion, been transposed from the boss 50b to 50a. Hence, fluidwill be discharged under pressure through the pipe 94a, shown in phantomoutline in FIGURE 5.

Attention is now directed to FIGURE 7 of the drawings wherein there isillustrated a modified form of rotor body generally designated 98. Therotor 98 is secured to shaft 100 and is adapted for rotation in thearcuate direction indicated by arrow 102, the rotor being locked to theshaft 100 by means of the set screw 104 which is disposed in a threadedbore in the rotor 98 as indicated. Along the peripheral surface of therotor 98, a plurality of arcuately spaced slots 106 are formed, eachslot having angularly disposed trailing and leading faces 108 and 110respectively. These faces are at an acute angle of between about 15 and25, and preferably about 20. The slots 106 further have a bottom surface112 which is spaced from the outer surface 114 a sufficient distance toaccommodate a roller 85 therewithin. When roller 86 is disposed incontact with the bottom surface 112, there is preferably a narrow gapbetween the trailing and leading faces 108 and 110 and the roller.

The trailing and leading faces 188 and 110 are preferably formed in aplanar configuration, and the faces nevertheless are disposed generallyalong .a plane passing through the central axis of the rotor. In otherwords, a plane which passes through the central axis of the rotor 98will also pass along both the trailing face 188 as well as the leadingface 110 of each of the individual slots 106. It will be appreciatedthat it is not essential that the individual trailing and leading facesbe formed with a planar surface, and the arcuate surfaces may be used aswell, however. It has been found that the planar faces more effectivelyrelieve the scuffing action which may otherwise result in connectionwith the roller devices during their operation. The radius of the areupon which the surfaces of the trailing and leading faces 108 and 110 issufiiciently great in order to prevent a substantial moment force beingapplied against the surface of the roller in the direction of thecylindrical surface of the pumping chamber. For a rotor having adiameter of 3.8 inches, and employing a roller having a diameter of0.675 inch, an arcuate surface having a radius of 0.175 inch has beenfound satisfactory. Other sizes will be in the same general proportion.

Inasmuch as the individual trailing and leading surfaces 108 and 110 aresymmetrically disposed relative to the central axis of the rotor, therotor may be readily turned for reversal when desired. Rotor 98 willnormally employ the shallow cavity 60, as shown in FIGURE 3, whichcommunicates with a small passageway 62 leading from a space or void 64between the end wall 16 and the shaft seal 56 nearest thereto, the rotorshould be reversed in the chamber in order that the cavity 60 will be inthe proper relationship relative to the ports and seals.

Because of the uniform design of the rotor elements 70 and 98, it willbe possible to fabricate these components using powdered metallurgytechniques. Close or fine machining may not be required when thesetechniques are employed.

Therefore, the versatility of the pump of the character disclosed hereinwill be readily appreciated. It will, of course, be understood thatvarious changes may be made in the form, details, arrangements, andproportions of the parts without departing from the spirit and scope ofthe invention as set forth in the appended claims.

What is claimed:

1. A fluid pump comprising:

(a) a housing having a cylindrical pumping chamber therein;

(b) said pumping chamber being defined by an inner circumferential walland a pair of spaced circular end walls;

(c) a rotor rotatably mounted within said pumping chamber and having itsaxis in offset parallel relation to that of said pumping chamber andhaving a width such as to extend from one of said circular end walls tothe other;

(d) said rotor having a plurality of roller receiving slots ofpredetermined depth formed into and across the circumferential surfacethereof;

(e) a roller having a predetermined diameter disposed for free rotationin each of said roller receiving slots and having an axial lengthextending from one of said circular end 'walls to the other;

(f) arcuately spaced inlet and outlet ports communicating with saidchamber through arcuately spaced openings in said walls; and

(g) the said roller receiving slots in said rotor having a bottomsurface with a generally planar central portion and generally angularlyoriented planar leading and trailing faces disposed in radiallyoutwardly diverging relationship, one to another, with the said trailingface being disposed substantially along a radius line of said rotor, andwith the sum of said predetermined depth and a gap between said rotoredge and said inner circumferential wall and being substantially equalto said predetermined diameter and with the slot width at a distanceradially outwardly from the base of said slot equal to the radius ofsaid roller being greater than the diameter of said roller, thearrangement being such that simultaneous contact is possible betweensaid roller, said bottom surface, and one only of said leading andtrailing surfaces.

, faces are spaced apart 2. The fluid :pump as defined in claim 1 beingparticularly characterized in that the outer edge of said trailing facesurface is spaced from said inner circumferential surface a distancewhich is always less than the radius of said roller.

3. The fluid pump as defined in claim 1 being particularly characterizedin that said leading and trailing by said bottom surface a distancewhich exceeds the radius of said roller, and are spaced apart at a pointradially outwardly from the bottom surface equal to the radius of saidroller by a distance substantially equal to the diameter of said roller.

4. A fluid pump comprising:

(a) a housing having a cylindrical pumping chamber therein;

(b) said pumping chamber being defined by an inner circumferential walland a pair of spaced circular end Walls;

(c) a generally cylindrical rotor rotatably mounted within said pumpingchamber and having its axis in offset parallel relation to that of saidpumping chamber and having a width such as to extend from one of saidcircular end walls to the other;

(d) said rotor having a plurality of roller receiving slots ofpredetermined depth formed into and across the circumferential surfacethereof;

(e) a roller having a predetermined diameter disposed for free rotationin each of said slots and being spaced from, but in close clearancewith, the sides thereof and extending from one of said circular endwalls to the other;

(f) arcuately spaced inlet and outlet ports communicating with saidchamber through arcuately spaced openings in said walls; and

(g) the said roller receiving slots in said rotor having a bottom andgenerally angularly oriented generally planar leading and trailing facesdisposed at an acute angle to one another in radially outwardlydiverging relationship with the said trailing surface beingsubstantially along a radius line of said rotor, and with the sum ofsaid predetermined depth and a gap between said rotor edge and saidinner circumferential wall being substantially equal to saidpredetermined diameter and with the slot width at a distance radiallyoutwardly from the base of said slot equal to the radius of said rollerbeing greater than the diameter of said roller, the arrangement beingsuch that simultaneous peripheral contact occurs between the surface ofsaid roller and said bottom surface and one only of said leading andtrailing surfaces.

5. The fluid pump as defined in claim 4 being particularly characterizedin that said roller receiving slots define a roller receiving cavityhaving a spacing between leading and trailing faces greater than thediameter of said roller as measured along a plane passing through thecentral axis of said roller and outwardly from the base of said slot adistance greater than the radius of said rollers.

6. The fluid pump as defined in claim 4 being particularly characterizedin that said acute angle ranges from between 30 and 50.

7. The fluid pump a defined in claim'6 being particularly characterizedin that said acute angle ranges from between about 35 and 45.

8. The fluid pump as defined in claim 6 being particularly characterizedin that said acute angle is 45.

9. A fluid pump comprising:

(a) a housing having a cylindrical pumping chamber therein;

(b) said pumping chamber being defined by an inner circumferential walland a pair of spaced circular walls;

(0) a rotor rotatably mounted within said pumping chamber and having itsaxis in offset parallel relation to that of said pumping chamber andhaving a width such as to extend from one of said circular end walls tothe other;

(d) said rotor having a plurality of roller receiving slots ofpredetermined depth formed into and across the circumferential surfacethereof and having a bottom and angularly oriented leading and trailingfaces;

(e) a roller disposed for free rotation in each of said slots having adiameter equal to the sum of said predetermined depth and the gapbetween said rotor edge and said inner circumferential wall, and beingspaced from each of said faces along the entire depth thereof in andextending from one of said circular end walls to the other;

(f) arcuately spaced inlet and outlet ports communicating with saidchamber through arcuately spaced openings in said walls;

(g) the said leading and trailing faces being disposed at an acuteangle, one to another, in radially outwardly diverging relationship, thesaid trailing face being disposed substantially along a radius line ofsaid rotor and terminating in a surface arranged in closely spacedrelationship along a predetermined portion of the inner surface of saidcircumferential wall between said inlet and outlet ports; and

(h) the arrangement being such that simultaneous conthat occurs betweenthe surface of said roller, said bottom surface and only one of saidleading and trailing surfaces.

10. The fluid pump as defined in claim 9 being particularlycharacterized in that the surface along which said trailing faceterminates is an arcuate surface forming a running barrier along saidpredetermined portion of said circumferential wall substantially midwaybetween said arcuately spaced inlet and outlet ports.

11. A. fluid pump comprising:

(a) a housing having a cylindrical pumping chamber therein;

(b) said pumping chamber being defined by an inner circumferential walland a pair of spaced circular end walls;

(c) a rotor rotatably mounted within said pumping chamber and having itsaxis in offset parallel relation to that of said pumping chamber andhaving a width such as to extend from one of said circular end walls tothe other;

(d) said rotor having a plurality of roller receiving slots ofpredetermined depth formed into and across the circumferential surfacethereof;

(e) a roller having a predetermined diameter disposed for free rotationin each of said slots and extending from one of said circular end wallsto the other with the predetermined diameter being substantially equalto the sum of said predetermined depth and the gap between said rotoredge and said inner circumferential wall;

(f) arcuately spaced inlet and outlet ports communicating with saidchamber through arcuately spaced openings in said walls; and

(g) the said roller receiving slots in said rotor having generallyangularly oriented leading and trailing faces disposed in radiallyoutwardly diverging relationship, one to another, with the said leadingand trailing faces each being disposed substantially along planespassing through the central axis of said rotor, the arrangement beingsuch that simultaneous contact occurs between the surface of saidroller, said bottom surface and only one of said leading and trailingsurfaces.

12. The fluid pump as defined in claim 11 being particularlycharacterized in that said angularly oriented leading and trailing facesare disposed at an angle of between about 15 and 25, one to anotheralong and adjacent the base thereof.

13. The fluid pump as defined in claim 12 being particularlycharacterized in that said angle is substantially 20.

N. A fluid pump comprising:

(a) a housing having a cylindrical pumping chamber therein;

(b) said pumping chamber being defined by an inner circumferential walland a pair of spaced circular end walls;

(0) a rotor rotatably mounted within said pumping chamber and having itsaxis in offset parallel relation to that of said pumping chamber andhaving a width such as to extend from one of said circular end walls tothe other;

(d) said rotor having a plurality of roller receiving slots ofpredetermined depth formed into and across the circumferential surfacesthereof;

(e) a roller having a predetermined diameter substantially equal to thesum of said predetermined depth and the gap between said rotor edge andsaid inner circumferential wall and being disposed for free rotation ineach of said slots and extending from one of said circular end walls tothe other;

(f) arcuately spaced inlet and outlet ports communicating with saidchamber through arcuately spaced openings in said walls; and

(g) the said roller receiving slots in said rotor having a planar bottomface and generally spaced apart planar leading and trailing faces, thatportion of said leading and trailing faces spaced radially outwardlyfrom the bottom face thereof by a distance at least equal to the radiusof said roller being spaced apart a distance which is substantiallygreater than said predetermined diameter, the arrangement being suchthat simultaneous contact is possible between said roller and bottomsurface and one only of said leading and trailing surfaces.

References Cited by the Examiner UNITED STATES PATENTS 1,271,585 7/1918Klise 103-136 2,159,941 5/1939 Guinness 103-136 2,737,121 3/1956Badalini 103-136 2,765,745 10/1956 Sadler et al. 103-136 3,016,0191/1962 Rineer 103-136 3,025,802 3/1962 Browne 103-136 3,072,067 1/1963Beller 103-136 3,119,345 1/1964 Cook 103-136 FOREIGN PATENTS 613,60912/1960 Italy.

DONLEY J. STOCKING, Primary Examiner. W. J. GOODLIN, Assistant Examiner.

1. A FLUID PUMP COMPRISING: (A) A HOUSING HAVING A CYLINDRICAL PUMPINGCHAMBER THEREIN; (B) SAID PUMPING CHAMBER BEING DEFINED BY AN INNERCIRCUMFERENTIAL WALL AND A PAIR OF SPACED CIRCULAR END WALLS; (C) AROTOR ROTATABLY MOUNTED WITHIN SAID PUMPING CHAMBER AND HAVING ITS AXISIN OFFSET PARALLEL RELATION TO THAT OF SAID PUMPING CHAMBER AND HAVING AWIDTH SUCH AS TO EXTEND FROM ONE OF SAID CIRCULAR END WALLS TO THEOTHER; (D) SAID ROTOR HAVING A PLURALITY OF ROLLER RECEIVING SLOTS OFPREDETERMINED DEPTH FORMED INTO AND ACROSS THE CIRCUMFERENTIAL SURFACETHEREOF; (E) A ROLLER HAVING A PREDETERMINED DIAMETER DISPOSED FOR FREEROTATION IN EACH OF SAID ROLLER RECEIVING SLOTS AND HAVING AN AXIALLENGTH EXTENDING FROM ONE OF SAID CIRCULAR END WALLS TO THE OTHER; (F)ARCUATELY SPACED INLET AND OUTLET PORTS COMMUNICATING WITH SAID CHAMBERTHROUGH ARCUATELY SPACED OPENINGS IN SAID WALLS; AND